This invention relates to a lens design for optical Fourier transform systems, and more particularly to a Fourier transform lens system of the configuration rotationally symmetric with respect to the optical axis thereof and in which the object plane is placed in the primary focal plane and the aperture plane in which the spectrum of the object is formed coincides with the secondary focal plane to optically realize the Fourier transform relationship while effecting good state of simultaneous correction of various aberrations accompanied with imaging of the object and formation of the spectrum.
Optical Fourier transform systems are used to obtain a spectral distribution F(x') which is generated through a diffraction of an object such as that having a transmission coefficient, f(x), or further to obtain a reconstructed image of the object which is a diffraction pattern of the said spectrum. In realizing these processes by use of an actual lens, this lens is required to produce an image of the object and an image of the pupil in good states simultaneously.
Because of fundamental relations between aberrations accompanied with imaging of the object and also imaging of the pupil, it is thought impossible, within the conventional common sense of optics, to correct aberrations of these two sort of imaging in good states simultaneously.
The object of the present invention is to provide a lens system capable of achieving Fourier transformation optically in satisfactory manner, based on a theoretical finding that correction of aberrations in the two sorts of imaging can be attained simultaneously without any contradiction.